BCD436HP: Connecting Headphone Jack to Aux-in on Stereo; bad idea?

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jdcaples

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I left scanning when my region went to trunking a couple of decades ago.

I started up again after a major crime took place about 1 block from my home. At first I was just listening to broadcastify feeds, then buying a BCD436HP because the broadcastify feed wasn't meeting increasing addiction needs.

The BCD436HP is the most sensitive piece of equipment under my care. The forum is replete with "do not" guidance like "don't charge your batteries in the scanner."

To me, that's counter-intuitive. Even the manual indicates it's ok to do so, but there are enough anecdotal data points to indicate that my common sense doesn't apply to my scanner.

As such, I have a question: Is it ok to use a patch cord between the head set jack on my scanner to the Aux-In port on my Logitech I-pod-speaker dock gizmo.

The Logictech device accepts input from other devices - via a 3.5mm input jack - like my BOSS DB-90 Metronome.

Should it be the same with the scanner, or is there something I don't know about that makes making that connection a bad idea?

Thanks!

-Jon

PS: the problem I think this will solve is that sometimes, even at full volume, I can't hear some radio operators.
 
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Wackyracer

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I have a question: Is it ok to use a patch cord between the head set jack on my scanner to the Aux-In port on my Logitech I-pod-speaker dock gizmo.

The Logictech device accepts input from other devices - via a 3.5mm input jack - like my BOSS DB-90 Metronome.

Should it be the same with the scanner, or is there something I don't know about that makes making that connection a bad idea?

Thanks!

-Jon

PS: the problem I think this will solve is that sometimes, even at full volume, I can't hear some radio operators.
You should be fine as long as you turn the volume down on the scanner first, then slowly turn it up but no more then needed to get good undistorted audio out of the logitech device at any volume.
 

JamesO

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jonwienke

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Line-in and headphone voltage levels are roughly equivalent, so you aren't likely to have issues from excessive signal voltage from the scanner damaging the speaker dock. Do pay attention to the scanner volume level vs volume adjustments on the dock. Gain staging (https://ask.audio/articles/5-gain-staging-mistakes-to-avoid) is important to consider whenever connecting audio devices together.

Where you may run into trouble is with signal grounding. Uniden uses a push-pull audio amplifier output. This has the advantage of doubling the output voltage going to the speaker, but it also means that if you connect any of the audio output wires to ground, you can damage the amplifier. This is not an issue if the scanner is running off battery power, but if you have the scanner connected to USB power while connected to the dock, you can blow out the scanner audio amp. To prevent this, you should use a ground loop isolator between the scanner and the dock. (https://www.amazon.com/Maceton-Preminum-Filtering-Isolator-detachable/dp/B01H1X5PIA/)
 

budevans

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For the past 2 years plus years, I've run my 436 at home connected to a PC speaker amp. In my car I use a patch cable plugged into the Aux input of my cars stereo system. In both cases the 436 is getting power through the USB cable.

The home amplified PC speaker is a $7 Inland brand 3 watts, that I purchased at Micro Center.

The car patch cable cost me $1 from Just A Buck. I use a USB cigarette lighter plug for power. I start the car first, then turn on the scanner. I turn off the scanner first, then I turn off the car. Better safe than sorry.

Both setups work great. Huge improvement verses the scanners internal speaker.

Additional Note: The cigarette lighter plug in my car is designed to be used by an audio source that feeds the stereo system. It's filtered and turns power on and off with the car.
 
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jonwienke

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That's great for you, but it all depends on whether the audio input of the device is connected to the same ground as the 436 power supply. If they are connected, you'll need an isolator or you'll damage the 436 output amp. If not, you can plug and play.
 

jdcaples

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My take-away is:

1) Turn the volume down to zero on the scanner and then turn off the scanner.

2) Make the connection and power up the scanner and slowly ratchet up the volume

3) I won't damage the scanner long as I only use battery power until the GLI arrives and sits between the scanner and the amplifying sound device. Yes?

Wow. In my five point one decades of life, I've never lost a piece of electronic gear to a ground loop; now is no time to start. Reading this makes me feel like the luckiest human in history.

I'm glad I asked.

Thank you, everyone.

-Jon
 

jonwienke

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Yes, yes, and yes, except that you don't need to power down the scanner. Turning the volume down and gradually increasing it after connecting is sufficient.
 

slicerwizard

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Wow. In my five point one decades of life, I've never lost a piece of electronic gear to a ground loop; now is no time to start. Reading this makes me feel like the luckiest human in history.
A ground loop isn't going to take out any of your gear. The Uniden audio circuits are designed with this issue in mind. The "ground" side of the headphone jack typically has a DC blocking cap and there are current limiting series resistors used as well, so no, the sky isn't falling.
 
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